According to the Green Bay Press-Gazette, Barclay tore his right anterior cruciate ligament while participating in a blitz drill.

Though the Packers have yet to provide an official diagnosis, head coach Mike McCarthy did confirm after Tuesday's practice that Barclay, who started 14 games at right tackle in place of an injured Bryan Bulaga last season, did hurt his right knee.

"He got himself in a bad position. He's being evaluated," said McCarthy. "We'll know more probably [Tuesday night]. We'll wait to see what we're dealing with. They don't come any better than him. I just hope it's not serious."

Barclay has made 18 starts overall since making the Packers as an undrafted free agent in 2012 and had been slated to serve as the team's swing tackle, a role that's now expected to be filled by 2011 first-round pick Derek Sherrod.